摘要：Geological adaptability matching design of a disc cutter is the prerequisite of cutter head design for tunnel boring machines(TBMs)and plays an important role in improving the tunneling efficiency of *** main purpose of the cutter matching design is to evaluate the cutter performance and select the appropriate cutter *** this paper,a novel evaluation method based on multicriteria decision making(MCDM)techniques was developed to help TBM designers in the process of determining the cutter *** analytic hierarchy process(AHP)and matter element analysis were applied to obtaining the weights of the cutter evaluation criteria,and the fuzzy comprehensive evaluation and technique for order performance by similarity to ideal solution(TOPSIS)approaches were employed to determine the ranking of the cutters.A case application was offered to illustrate and validate the proposed *** results of the project case demonstrate that this method is reasonable and feasible for disc cutter size selection in cutter head design.

摘要：Wind barriers have attracted significant attention as an effective measure to ensure train safety under ***,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully *** determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal *** shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel *** results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D ***,with the increase in H,ΔCp first increased and then ***,these three factors must be considered during the installation of wind ***,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>*** on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant ***,the optimal values of R and H were determined to be 20%and 110 mm,*** when R=40%,H=85 mm,the train was relatively unsafe under these such *** findings of this study provide significant guidance for the structural design of wind barriers.

摘要：A calculation formula of thermal-hydro-mechanical(THM)coupling crack initiation rate for brittle rock was derived based on the energy conservation *** self-designed THM coupling fracture test with conductive adhesive electrical measurement method was applied to measuring the THM coupling crack propagation rate of brittle rock *** results show that both calculation and test results of crack initiation rate increased with increase of the temperature and the hydraulic *** are almost in good agreement,which can prove validity of the calculation formula of THM coupling crack initiation rate.

摘要：Compared with traditional solid-state drives(SSDs),open-channel SSDs(OCSSDs)expose their internal physical layout and provide a host-based flash translation layer(FTL)that allows host-side software to control the internal operations such as garbage collection(GC)and input/output(I/O)*** this paper,we comprehensively survey research works built on OCSSDs in recent *** show how they leverage the features of OCSSDs to achieve high throughput,low latency,long lifetime,strong performance isolation,and high resource *** categorize these efforts into five groups based on their optimization methods:adaptive interface customizing,rich FTL co-designing,internal parallelism exploiting,rational I/O scheduling,and efficient GC *** discuss the strengths and weaknesses of these efforts and find that almost all these efforts face a dilemma between performance effectiveness and management *** hope that this survey can provide fundamental knowledge to researchers who want to enter this field and further inspire new ideas for the development of OCSSDs.

摘要：Several antennas based on cylindrical array and uniform hexagonal array are designed and fabricated on flexible *** validate the designed prototypes,the antennas are fabricated and their performance is *** highlight scheme is to improve the signal performance and electromagnetic field distribution by appropriately changing the parameters of the antennas array,signal frequencies,and steering *** proposed antennas array is capable of applying shaping radiation band technique to generate tunable power and radiation *** distribution of the field,and the bit-error-rate transmigration coefficient characteristics are *** results show that the proposed scheme can achieve better performance by searching the optimal parameters of antenna array.

摘要：An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics （CFD） analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories： the meridional contour design vari- ables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network （ANN） techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller per- formance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.

摘要：Traditional parafoil homing usually uses a point as object. As the mobility of parafoil is limited by its glide ratio and wind, in some cases when the parafoil scatter area is large, or the glide ratio of parafoil is small, the deviation of its landing point to object point will be arduous to control. Accordingly, during these situations, when parafoil is used in recovery of spacecraft or satellite, the landing area of parafoil can be set as a rectangle, and the object of parafoil can be set as a line segment. The thesis of this work is designing an algorithm for parafoil homing using line segment as object. The algorithm of wind velocity and direction calculation in different flying segments was also investigated. The algorithm designed navigates the parafoil to land into the predestined area and largely reduce the probability of recovery loads falling to unwanted area to damage houses and people.

摘要：Non-uniform rational B-spline(NURBS)curves are combined with the Kriging model to present a prediction method of the rail grinding profile for a grinding *** a worn rail profile is a free-form curve,the parameterized model of a rail profile is constructed by using the cubic NURBS *** the removed area of the rail profile cross-section by grinding as the calculation index of the grinding amount,the grinding amount calculation model of a grinding wheel is established based on the area integral formula of the cubic NURBS *** predict the grinding amount of a grinding wheel in different modes,a Kriging model of the grinding amount is constructed,taking the travel speed of a grinding train,the grinding angle and grinding pressure of a grinding wheel as the variables,and considering the grinding amount of a grinding wheel as the *** this basis,the prediction method of the rail grinding profile is presented based on the order-forming *** effectiveness of this method is verified based on a practical application.

摘要：We propose a thoroughly optimal signal design strategy to achieve the Pareto boundary （boundary of the achievable rate region） with improper Gaussian signaling （IGS） on the Z-interference channel （Z-IC） under the assumption that the interference is treated as additive Gaussian noise. Specifically, we show that the Pareto boundary has two different schemes determined by the two paths manifesting the characteristic of improperly transmitted signals. In each scheme, we derive several concise closed-form expressions to calculate each user＇s optimally transmitted power, covariance, and pseudo-covariance of improperly transmitted signals. The effectiveness of the proposed optimal signal design strategy is supported by simulations, and the results clearly show the superiority of IGS. The proposed optimal signal design strategy also provides a simple way to achieve the required rate region, with which we also derive a closed-form solution to quickly find the circularity coefficient that maximizes the sum rate. Finally, we provide an in-depth discussion of the structure of the Pareto boundary, characterized by the channel coefficient, the degree of impropriety measured by the covariance, and the pseudo-covaxiance of signals transmitted by two users.

摘要：The purpose was to clarify the relationship between the main process parameters of micro-plasma cladding and the comprehensive quality(geometry,microstructure and wear rate of cladding track).Self-fluxing ferrous alloy powders were fabricated on Q235 *** on the uniform design,the distribution of the experimental samples was designed reasonably in the sample space,which greatly improved efficiency and reduced *** a series of microstructural characterization,there was no difference in the phase composition of all samples,but the average grain size had a significant difference,which resulted in the change of wear *** the relationship among micro-hardness,average grain size and wear rate of the track had also been ***,an optimization model was established and the optimal process parameters were obtained with excellent wear rate under the geometric *** correctness of optimization model was verified by experiments.